The exhaust lines of vehicles equipped with heat engines typically comprise catalytic purification members, for example making it possible to convert NOx, CO and hydrocarbons into N2, CO2 and H2O. Such members are only effective when the catalytic material is at a minimum temperature.
A problem arises upon starting the vehicle, when the engine is still cold and the exhaust gases produced are at an insufficient temperature to heat the catalytic material to a sufficient temperature for the purification members to become active.
To resolve this problem, it has been proposed to make the substrate of the purification members from a material with a relatively low electrical resistance, and to circulate a strong electrical current in this substrate when starting the engine, or even before starting the engine, so as to cause rapid heating of the substrate, and in this manner, of the catalytic material deposited thereupon. Such a purification member is known from U.S. Pat. No. 8,715,579.
However, the known solutions are not fully satisfactory. Indeed, the electrical power is generally poorly distributed within the substrate, which on the one hand causes a nonhomogeneous heating of the purification member which, as a result, retains downgraded performance levels even after having been electrically heated, and on the other hand, breaking of said substrate by differential expansion.